Automatic telephone system



Nov. 1 ,1925. 1,560,725

w. T..POWELL AUTOMATIC TELEPHONE SYSTEM Filed 'Jan. 25, 1922- 2 sheets-sheet 1 6 v (0 55 a M..

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SELECTOR LINE SWITCH.

INVENTOR WINFRED T. POWELL.

' ATTORNEY T.' POWELL, AdToMAT'Ic' TsLgPg'oNE s'grs'rm Fi-led m. 25, 1922 2 Sheets-Shet 2 INVENTOR w: NFRED T POWELL BY ATTORNEY Moi Patented Nov. 10, 1925.

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wwesmmseqm To alliwhom ifmag concern:

Be it known that I, Vi FRED T. PO ELL,

V a citizen kit the United States; tesiding zttolw mef i e mini? 5 M9 311d; Stete of New fo lg have nvented centa n ne y'a nd; useful Improvements Automatic Tel'ephene Systems; of whi'elithe folleiving esszi y thnt felt-able nieans he 'i'dvided fei Causing the trunk; limiting; switches thereof to oveif busy tijunlgs but to seize ifdle trunks-1nd guafcl t hen against; intrusion all of which n nst he chine nifapidhndf ieli ahle manner.

Tliefni in feature of this intention is the arrangement of ei ieuits by Whiehti-nnk hunting switches n a y test and seize icl l'e trunks, ii itl fapid ity' necn a c y;

The drawings with 2p need at, the ht f en 1 d a ram ati i :6 re n a portion of a telephene systeni inc titling the present invention. At the 111)]261 left hand corner ofFig 1 there is lGRI'QS'QI ItiOCl .2 calgling'line and; the cii cu its o f z truiik linnt-f lllg' switch. individual t mnewmge the right (If the d tt-ecl line gn e i sd t Psra i e-r. ir u ts; lfe qr switch incorporatingthe piese it intention; j 'i'e m m fielil hEE J$Q i .-S sig ting circuits of connectorcswiteh a alled telephone line. 3 is a'tl'ieei etxeal showing ef the testing circuitsoffthe line switch ef Fig, 1 at the time, when the idle trunk isf being tested; The" lneehaiiic zil structure of theline switch may beisnhs tagi tinlly' sin ilnr to that cljsclosedin t0 G'leinent $151,107,153issne chAngust 1 1 191 3 while the eqnnecto end, switches may he of the st 'n'etnref' snhsten; tiall-y similar to that disclosed in the patent t o Keith, Ei jiekspn, and Erickson and #815,176 both issuedfMni ch 1-3, 1906;

After thisghi'ief desclfiptid n ofthe, in ven ti an and of the. niecln nical stijnctu e of the sxfgitehes it is believed that the invention will best be nndersteed by cteseribing the n lethed of establishing a tle hene connectipntifon a calling snhstation indicated at ten n izign et nemmn clbsed efl iio nnarlcen- 0f the magnet 7-, resistance to grounded"; hattei y The meter magnet Ms opeyetedf in this" circuit and ad val-nees' the line s vit-eli hl'nshes 931i), 1 1 and; 12 one step f x- 0in: their noiniali position into F engagement with the teinninzilsf of the first trunk eirc-u-i-t a. qpea il g inihisswitch. Letithe assumed t ia't'tliis ttill lk cii enitis busy} at-this'thpe; a sofidi i.n*wh iq s i i aby t s nse of q etentiat-qi-i-the test terminal 13- 015 this trunk. A's soon: as, the line switch is thus N A meets-1e 'oiin'cl itsiwinding contacts 14; {Win-Ettare aiitl" I ern et life and ha 0k 'cg'ntact of; inagnet 1 0m sistaneeftd 0 Cdlitflhl Q ftlns elrchit the intoi; magnet 7 eontinnes, to acl-i al ice the brushes-9 ,110; 11 and" 12' Of the line switch u-ntilf the test e qperzit-ed'l na siren-1 bfush 1'1 eneeiinters a test tenminal such I3- e f' an] idle'tlinnlc which; is characterized leg. resence ofpetentifal This potential on test ter1n-i na, l 13"is ap led front-the" see= 0nd Batten-3 D which is distinct troni the ether epeih ting battery diagrammatically i epneseiited and-1 designated C at sew 'er'al 'places, in-lfigs 1 and 2'. The batteries. Q

are of the same: voltage and each has a qs itiye ple I and a negative pole connected'to grpund asshown in Fig, 3- (hen this idle tmink; is/re'ached, a ci ycnit is closed from the secench battery D, lnidc lle contact and 'nifinatiirebf? i'el'ziy 17 ai'n iat-ure 1-8 and h'zieli cassette i'elsy 19-, condfuctoi; 15,; test ter-e he "elhsed 'Ltnd the instep magnet mindbdi Y Uncles the I hack e0ntaetdf mateft relay 6*. v

niinal' 13, test brush 11, upper winding of the cut-off relay 6, armature, front contact and winding of relay 5, armature and back contact of magnet 7, resistance to grounded battery. By reference to Fig. 3 it will be noted that the motor magnet 7 will be deprived of operating current since, it will be in the neutral wire of an arrangement which is analogous to the Edison three-wire system of current transmissionf The cut-off relay is energized in the circuit just described and immediately attracts its armatures to disconnect the line-relay 5 from the control of the calling line and to extend this line through its upper armatures and front contacts to the line switch brushes 9 and 10. At the lowermost armature of this relay, the operating circuit of the motor magnet 7 is opened. As soon as the calling line is extended to'the line switch brushes in themanner described, the impulse relay 20 of the selector switch is energized in a circuit traceable from grounded battery, right hand winding of this relay, uppermost back contact and armature of relay 19, through line switch brush 9, front contact and armature of relay 6, over the upper side of the calling line and substation circuits in series, over the lower side of the calling line, armature and front contact ofrelay 6, brush 10, inner upper armature and back contact of relay'19, left hand winding of relay 20 to ground. The impulse relay is energized in this circuit and completes anoperating-circuit for the slow releasing relay 17 from grounded battery winding of this relay, left hand front contact and armature of relay 2G,armature 21 and back contact of relay 19 to ground. 1 As soon as relay 17 is operated it closes a locking circuit for the cut-off relay 6 extending from. grounded battery,

lower Winding, armature and front contact of relay 6, holding brush 12, conductor 22, outer armature and contact of relay 17 to ground. a i

The apparatus and the circuits. are now in condition to receive the series of impulses corresponding to the first digit of the wanted number. In response to each of these impulses the impulse relay 2O vibrates its armatures and thereby completes an operatingcircuit for the primary motor magnet 23, from grounded battery, winding of this magnet, change over relay 24 innermost contact and armature ofirelay 17 back contact and armature of impulse relay 20, armature 21 and contact of relay 19 to ground; lvVhen this circuit is first completed the changeover relay 24 is operated and holds its armature attracted during the remainder of the series of impulses to open the operating circuit of the secondary magnet 25. In response-to each closure of the operatingcircuit of the primary magnet it advances the selector brushes 26, 27, 28 and one step in their prin'iary direction. It should be noted at this time that the operating circuit of the release magnet 30 is held open at the innermost back contact and armature of relay 17 to preventthe release of the selector switch. I I

At the close of the first series of impulses, the impulse relay 20 will hold its armatures attracted for a relatively long period, with the result that the operating circuit for the change-over relay 24 will be interrupted and this slow releasing relay will eventually retract its armature, at which time a circuit is closed from ground, oif-normal contacts 31 (now closed), arn'iat-ure and back contact of the change-over relay 2 1, winding of the interrupter relay 32, conductor 33, lowermost armature and back contact of relay 19, right hand contact and arn'iature of relay 20, armature and back contact of the secondary motor magnet 25, resistance, to grounded battery. Relay 32 is energized in this circuit, and closes an energizing circuit for the secondary motor magnet 25 from grounded battery winding of this magnet, front con tact and armature of relay 32, back contact and armature of relay 2%, ofi normal contacts 31 to ground. Under the control of this circuit the secondary motor magnet 25 advances the selector switch brushes one step in their secondary direction into engagement with the first trunk circuit of the selected group of trunks. It will be noted that secondary magnet 25 on energization opens the operating circuit of the relay 32 which immediately deenergizes to interrupt the operating circuit of the secondary motor magnet 25.

Let it be assumed that the first trunk of the selected group is busy at the time when test brush 28 engages its test'terminal similar to 34;. Such busy condition is indicated by the absence of potential on its test terminal. The relay 32 will then be again energizedin its operating circuit already de scribed and Whenit attracts its armature, it will complete an actuating circuit for the secondary motor magnet 25 in the manner already described, which will advance the selector switch brushes into engagement with the second trunk of the selected group of trunks.

Let it be assumed that the first idle trunk tested by the test brush 28 is the trunk appearing in Figs. 1 and 2. When this trunk is tested it will be characterized by the presence ofbattery potential thereon applied from the positivepole of the secondary battery 35, outer back contact and armature of relay 36, conductor 37, terminal 34, test brush 28, upper winding of relay 19, right hand contact and armature of relay 20, armature andbackcontact of the secondary motor magnet 25 to the negative pole of the first battery to ground. It will thus be seen that. the interrupter relay 32..is in the neutral wire oi the. circuit arrangement analogous to that schematically shown in Fig. 3. The relay 32 doesnot receive sufiicient current to one glue and holds open the operating; circuit of the secondary motor magnet. The relay 1:9 will be energizedin the circuit already described. and, at its. up: per armature and back contacts removes. the windings of the impulse relay 20. from the control oi the calling line. At the upper-' most armature and iront contacts of relay-- 19 the calling line is extended through the selector brushes 26 and 27 and over the two sides of the selected trunk, through the winding of impulserelay 38 to grounded hattery'and tl'irough the winding of the in pedance coil 39 to ground. Under the controlof this circuit the relay 38 is energized to close a circuit which operates the slow releasing relay 36; This last mentioned relay when operated closes a holding circuit for relay 19 which circuit is traceable from ground, armature and front contact of relay 3 6, conduct-or 40, holding blUSl-l- 29, innermost lower armature, 'iront contact and winding of relay 19 to groundedbattery.

The connector switch circuits are now in conditionto receive the first series of impulses coresponding to the tens digit of the wanted number, in response to eacho'f these impulses the impulse relay 38' vibrates its armature. At each retraction of its armature a circuit is closed fromground, armature and back contactof the impulse'relay, armature and front contact of relay Winding of the change-overrel'ay ll, sideswitch wiper 42 in its first position, winding or the primary motor inag-net to grounded battery. The magnet 43 is energized in this circuit and advances the connector switch brushes 4L4, e5 andLG one step in their primary direction to select the group o'l -rlines including the wanted line; 'On the ener gi'z-a-tion jot the change-over relay ll, the escape magnet 47 is operated but at the close of this series of impulses the'i-mpulse relay, 38 will hold: its armature attracted for a relatively long interval which willcause the change-over "relay 41 to 'deenerg-ize and thereby open the operating circuit of the escape magnet 47'. This magnet thereupon deenergizes and advances the idle switch wipers into their second position,

The subscriber at A thereupon o aerat'es his dial sender to transmit aseries of un; pulses correspond ng to the units digit-o f the Wanted number. In response to each of these units impulses, the impulse relay.

3,8 againvibrates as armature; and-"oneach retraction thereof completes a circuit from ground, armature and back contact of relay 38;, armature and'iront con-tact off relay 36, winding of the change-over-relay' at 1;, "side switch wiper 4:2 in its'second position, lower the called s contact and armature. oi? test. relay .t ,-.w nle mg, of the secondary; motor magnet 4:9. to. groundcdqbattery,

The changeover relay; 4.111

thiscircuit and,rema nsenergized du mg the step; by step over the terminals of; thelines of the selected group until theterminals: ,Oi

secondary motor magnet 4:9,; isiconipleted and it advances the, connector, switch brushes the wanted linenareireache'dr 10,11 the-com:

pletion of this,series-ofimpulses, the changeoverqrelay 451' deener'giz'es; in" the-manner already described, and if-the Wantedlineis idle the escape magnet; 41"? will; deenergize and.- advance. the side. switch Wipers: into their third position. .r

At this. time ringing curr n is applied-.130

the calledline tliroiighlthe 'ringiingmachime,

generally designated; 50, resistance. 5.1;, trip.- magnet 52, si'dexswitch wiperbh, com nector brush- 44, upper side *oii the called line and'called substation circuits, through the lower side ot the called; line, connector i brush 45 and the side switch wiper 5,4: in I its third position to grounds 'Ringingucunrent is applied over 'this' circtrit. untilthe called party responds, whereupon. the, trip relay '52 receives sufficient current tox-heenergized and attracts its armature, this shunts the escape magnet, to eflect (ileenergization and the consequent advance if a the slide p 'Q fourth? or talking position.

Talking current for the calling party. is

supplied tl iroug lt the windingso-fi'lthel *i mlpeda-nce coil 39, and winding 031% the impulse relay 38, while talking battery is applied to iibstation through i the.-. \viiid%ings oftheimpedanc'e coi l 55.

If the called'line isbusy at he ti ie when the test brush id-engages its' test t l'll lHa-l 5 6, this terminal vil-l he characterized l ly ground potential applied-through theofi; o norm'al contacts '57 of the line switch indri' vidual to the called line. Zltwill'- be 1 recalled that the test of the cabled Line is made 'wlien the side switch wipers are in their second positioin so that when. thechaiigeover relay 41 deenerglzes, the escape magnet 47 18 held operated in a circuittraceable from grounded battery, resistance, winding of this magnet, con'tinultyl spring: and back contact of relay 4:1, winding ot the) relay 48, its conti'nuity s'pr ing and back contact,iside switch wiper 58; inits second pesitiiomtest brush 46 test termin al 5 6 to; ground over the remainder or the circuit already descr1hed it the wa-nted'l ine'h-as or1g1nateda 1 call or through a multiple terminal of 56,

' this circuit and the test relay a8 is operated in series therewith to close a locking circuit including a. portion of the circuit already described, winding of this relay, its continuity spring and inner armature, oilnormal contacts 59 to ground. The escape magnet 4L7 is thus held energized to maintain the side switch-wipers in their second position to prevent the signaling of the busy called line. The test relay 4:8 is also held opera-ted until the connection is released and applies a source of busy current from the source B Z over the conductor 60, armature and front contact of the testrelay 48 to the calling line to inform the subscriber thereat that the called line cannot be seized.

The release of the connection is efi'ected by the restoration of the receiver to the switch hook of the calling station. This interrupts the energizing circuit of the impulse relay 88, which deenergizes and shortly afterwards causes the slow releasing relay 36 to retract its armatures. The connector switch will thus be released due to the energization of the release magnet 62 in a circuit closed from grounded battery, winding of this magnet, off-normal contacts 63, back contacts and armatures of relays 36 and 38 to ground.

Also when relay 36 deenergizes it opens the holding circuit for the relay 19 which it has completed over conductor 40, relay 19, therefore, deenergizes and closes an operating circuit for the release magnet 80 of the selector from grounded battery, Winding of this magnet, off normal contacts 64, innermost back contact and armature of relay 17, back contact and armature of relay 20, armature 21 and back contact of relay 19 to ground. The release magnet 80 is operated in this circuit and effects the release of the selector switch in the wellknown manner. Also when relay 36 of Fig. 2 deenergizes it effects the release of the line switch, since the cut off relay 6 of this switch has been held operated in a circuit in multiple with that of the relay 19. Cut-off relay 6, therefore, deenergizes and the motor magnet 7 of the line switch operates to advance the brushes of the line switch until they reach their normal position. The operating circuit of the motor magnet 7 may be described as extending from ground, winding of this magnet, off-normal contacts 14-, lowermost armature and back contact of relay 6, armature and back contact of magnet 7 resistance, to grounded battery. It will thus be seen that the motor magnet 7 has a self interrupting operating circuit which is intermittently completed until the line switch is in its normal position, at which time the offnormal contacts 14 will be open and the contacts 8 will be closed. The apparatus and circuits are now in condition to complete a second connection.

lVhat is claimed is '1. Inan automatic telephone system, an incoming circuit, a plurality of outgoing circuits, an automatic switch for extending said incoming circuit to any of said outgoing circuits, a motor magnet for operating said automatic switch, a plurality of 'separate batteries with connections therefor, means including said motor magnet, one of said batteries and one of said connections for operating said automatic switch, and means including both of said batteries and their connections for disabling said motor magnet.

2. In an automatic telephone system, an incoming circuit, a plurality of outgoing circuits, an automatic s itch for extending said incoming circuit to any of said outgoing circuits, a motor magnet for said switch, means including one battery for operating said motor magnet, and means including a second battery co-operating with said first battery to disable said motor magnet.

3. In an automatic telephone system, an incoming circuit, a plurality of outgoing cir-. cuits, an automatic switch for extending said incoming circuit to any of said outgoing circuits, a motor'magnet for operating said automatic switch, means including one battery and a circuit for operating said motor magnet, a relay controlled over the two sides of said incoming circuit in seriesto'complete the mentioned operating circuit of said motor magnet, and a second battery arranged to be connected in series with said first battery for disabling said motor mag: net.

4. In an automatic telephone system, an incoming circuit, a plurality of outgoing circuits, an automatic switch for extending said incoming circuit to any of said outgoing circuits, a motor magnet for advancing said automatic switch, means including a circuit and one battery for operating said motor magnet and means including a second battery and a conductor connected to said first circuit for stopping said motor magnet with its. automatic switch in engagement with a desired outgoing circuit.

5. In an automatic telephone system, an incoming line, a plurality of outgoing lines, an automatic switch for interconnecting said incoming line with any of said outgoing lines, a motor magnet for advancing said switch, a circuit for said motor magnet, a line relay operated over said incoming circuit to complete an operating circuit for said motor magnet, a second battery distinct from the first, and a cut-off relay initially energized from said batteries in series for disabling said line relay.

'6. In an auto1n=.1tic telephone system, an

incoming circuit, a plurality of outgoing circuits, an automatic swltch for intercon the disabling of said motor magnet, and an initial operating circuit for said cut-off relay seriallyincluding said first and secondb'atteries. f 7. In an automatic telephone, system, .an

incoming circuit,a plurality of outgoingc'ircuits, an automaticswitch connectmg'said incoming circuit with any of said outgoing circuits, n motor magnet for ac lva11cing said automatic switch, means including first battery and a circuit for operating said 1110- to r magnet to advance saidswitch, a second battery, a .cut-ofligrejlay for discontinuing the operation of the motormagnet when a certain outgoing circuit is seized by sa'idswitch, an o crating circuit for strident-(51 relay serialy includingsaid first and second bat-' teries, and .a holding circuit for said cat-0H relay.

8. In an automatic telephone system, an incoming circuit, a plurality ofontgoing circuits, an automatic switchior interconnecting said incoming circu t with any of'said outgoing circuits, a motor magnet for advancing said automatic switch, means including a first battery and a circuit for operating said motor magnet to advance said switch, a second battery, a cut-off relay for discontinuing the operation of the motor magnet when a certain outgoing circuit is seized by said switch, an operating circuit for said cut-ofi relay serially including said first and second batteries, and a holding circuit for said cut-oli relay including only one battery.

9. In an automatlc telephone system, an incoming circuit, a plurality of outgoing circuits, an automatic switch for intercom meeting said incoming circuit with any of said outgoing circuits, a motor magnet for advancing said switch to any outgoing circuit, a first battery, means includng a circuit and the first battery for operating said motor magnet, a line relay energized over,

said incoming circuit for completing said operating circuit, a cut off relay for deenergizing said line relay, and means including a second battery for eflecting the operation of said cut-ofl' relay. I

10. In an automatic telephone system, an incoming circuit, a plurality of outgoing circuits, an automatic switch for interconnecting said incoming circuit with any of said outgoing circuits, a motor magnet for advancing said switch to any outgoing clrcuit,

a first battery, mea s includi g a ircu t an said new ma n the firstbattery for operating said motor mag t, a'lmefrelay energized oversaid 111 comin'g' circuit foncom'p'leting said operatmagnety'means,includinga second battery for] characteriZ-ingthe trunks asidlefand testing means operated from the second battery'assooiated *with an idle trunk; a-n'd'i-n' seres with "said first battery for disabling auteur ru k! =1' 2.fIn an automatic telephone system, an incoming circuit, "a trunk hunting switch "in tic, switch in engagement with idle 111d feir stopping" said dividual to salid'incom-ing circuit,agroupof trrmks terminating in said trunk hunt in-g switch,"means including a first batteryand a motor magnet for advanfci-ng the automatic sw'itch,' means including a second "battery for characterizing trunks as idle, testing means successively connected to said trunks in the operat on "or said trunk-hunting switch, said testing means being effective on the testing of an idle trunk to discontinue the operation of said motor magnet, a secondary trunk hunting switch for each of said trunks, secondary trunks terminating in said secondary trunk hunting switches, means for operating each secondary switch including a secondary motor magnet and said first battery, and means 7 for stopping each secondary switch in engagement with an idle secondary trunk, said last mentioned ing switch, means including a first battery and a motor magnet for advancing theautomatlc' switch, means lncludmg a second bat-V tery for characterlzmgtrunks as dle, testing Vmeans successively connected to said trunks in theoperation of said trunk hunting switch, said testing means being effective on the testing of an idle trunk to dis continue the operation of said motormageach trunk, secondary trunks terminating in said secondary trunk hunting switches, means for operating each secondary switch including a secondary motor magnet and said first battery, and secondary means for not, a secondary trunk hunting switch for stopping each secondary switch in engagement with an idle secondary trunk, said last mentioned means serially including said first and second batteries.

14. In an automatic telephone system, an incoming circuit, a primary trunk hunting switch individual to said incoming circuit, primary trunks terminating in said primary switch, a'motor magnet for advancing said rimar switch over said trunks means in-' eluding a circuit and a first battery for operating said motor magnet, a second battery for characterizing trunks as idle, testing means responsive to the location of an idle trunk by said switch for disabling said motor magnet and for seizing said idle trunks, a secondary trunk hunting switch for each primary trunk, secondary trunks terminating in each secondary switch, means controlled over said incoming circuit and a selected trunk for directively operating its secondary switch, means including a secondary motor magnet for automatically operating said secondary switch toseize an idle trunk, operating means for said secondary motor magnet, including said first batter and means including said first and second batteries for causing said secondary switch to seize an idle secondary trunk.

15. In an automatic telephone system, an incoming line, a plurality of outgoing lines, an automatic switch for interconnecting said incoming line with any of said outgoing lir es, mechanism for controlling the advance of saidswitch, a first battery and a second battery, a circuit independent of said second battery but including said first battery and said mechanism for operating the same, and means including a second battery connection to said first circuit about said mechanism to stop the advance of said switch;

16. In an automatic telephone system, an incoming line, a plurality of outgoing lines, an automatic switch for interconnecting said incoming line with any of said outgoing lines, mechanism for controlling the advance of said switch, a circuit including a resistance and said mechanism for operating said mechanism, a line relay and a cutofi relay for said incoming line, said line relay functioning to close said circuit initially, and means including a second bat-' tery a winding of said line relay and a win ing of said cut-01f relay connected to first circuit about said mechanism to stop said switch, the value of said first mentioned resistance being substantially equal to the combined .resistancevalue of said line and cut-off relays. I

In witness whereof, I hereunto subscribe my name this 20th day of January A. D. 1922.

WINFRED T. POWELL. 

